From 980b0df8296cdec3692482c3efdbfa68036a1114 Mon Sep 17 00:00:00 2001
From: zeripath <art27@cantab.net>
Date: Tue, 15 Dec 2020 08:45:13 +0000
Subject: [PATCH] Standardise logging of failed authentication attempts in
internal SSH (#13962)
Continuing on from #13953 continue to improve and standardise
logging from internal SSH.
Also updates the fail2ban setup
Signed-off-by: Andrew Thornton <art27@cantab.net>
---
.../content/doc/usage/fail2ban-setup.en-us.md | 20 +++++++-
modules/ssh/ssh.go | 50 ++++++++++++++++---
2 files changed, 62 insertions(+), 8 deletions(-)
diff --git a/docs/content/doc/usage/fail2ban-setup.en-us.md b/docs/content/doc/usage/fail2ban-setup.en-us.md
index 5c5bdb9a28..790d4c020b 100644
--- a/docs/content/doc/usage/fail2ban-setup.en-us.md
+++ b/docs/content/doc/usage/fail2ban-setup.en-us.md
@@ -25,9 +25,27 @@ on a bad authentication from the web or CLI using SSH or HTTP respectively:
```log
2018/04/26 18:15:54 [I] Failed authentication attempt for user from xxx.xxx.xxx.xxx
```
+
```log
-2020/10/15 16:05:09 modules/ssh/ssh.go:188:publicKeyHandler() [E] SearchPublicKeyByContent: public key does not exist [id: 0] Failed authentication attempt from xxx.xxx.xxx.xxx
+2020/10/15 16:05:09 modules/ssh/ssh.go:143:publicKeyHandler() [W] Failed authentication attempt from xxx.xxx.xxx.xxx
```
+
+```log
+2020/10/15 16:05:09 modules/ssh/ssh.go:155:publicKeyHandler() [W] Failed authentication attempt from xxx.xxx.xxx.xxx
+```
+
+```log
+2020/10/15 16:05:09 modules/ssh/ssh.go:198:publicKeyHandler() [W] Failed authentication attempt from xxx.xxx.xxx.xxx
+```
+
+```log
+2020/10/15 16:05:09 modules/ssh/ssh.go:213:publicKeyHandler() [W] Failed authentication attempt from xxx.xxx.xxx.xxx
+```
+
+```log
+2020/10/15 16:05:09 modules/ssh/ssh.go:227:publicKeyHandler() [W] Failed authentication attempt from xxx.xxx.xxx.xxx
+```
+
```log
2020/10/15 16:08:44 ...s/context/context.go:204:HandleText() [E] invalid credentials from xxx.xxx.xxx.xxx
```
diff --git a/modules/ssh/ssh.go b/modules/ssh/ssh.go
index e8ed9029ce..4ba52d5653 100644
--- a/modules/ssh/ssh.go
+++ b/modules/ssh/ssh.go
@@ -134,14 +134,25 @@ func sessionHandler(session ssh.Session) {
}
func publicKeyHandler(ctx ssh.Context, key ssh.PublicKey) bool {
+ if log.IsDebug() { // <- FingerprintSHA256 is kinda expensive so only calculate it if necessary
+ log.Debug("Handle Public Key: Fingerprint: %s from %s", gossh.FingerprintSHA256(key), ctx.RemoteAddr())
+ }
+
if ctx.User() != setting.SSH.BuiltinServerUser {
- log.Warn("Permission Denied: Invalid SSH username %s - must use %s for all git operations via ssh", ctx.User(), setting.SSH.BuiltinServerUser)
+ log.Warn("Invalid SSH username %s - must use %s for all git operations via ssh", ctx.User(), setting.SSH.BuiltinServerUser)
+ log.Warn("Failed authentication attempt from %s", ctx.RemoteAddr())
return false
}
// check if we have a certificate
if cert, ok := key.(*gossh.Certificate); ok {
+ if log.IsDebug() { // <- FingerprintSHA256 is kinda expensive so only calculate it if necessary
+ log.Debug("Handle Certificate: %s Fingerprint: %s is a certificate", ctx.RemoteAddr(), gossh.FingerprintSHA256(key))
+ }
+
if len(setting.SSH.TrustedUserCAKeys) == 0 {
+ log.Warn("Certificate Rejected: No trusted certificate authorities for this server")
+ log.Warn("Failed authentication attempt from %s", ctx.RemoteAddr())
return false
}
@@ -151,7 +162,7 @@ func publicKeyHandler(ctx ssh.Context, key ssh.PublicKey) bool {
pkey, err := models.SearchPublicKeyByContentExact(principal)
if err != nil {
if models.IsErrKeyNotExist(err) {
- log.Debug("Principal Rejected: Unknown Principal: %s", principal)
+ log.Debug("Principal Rejected: %s Unknown Principal: %s", ctx.RemoteAddr(), principal)
continue principalLoop
}
log.Error("SearchPublicKeyByContentExact: %v", err)
@@ -172,33 +183,58 @@ func publicKeyHandler(ctx ssh.Context, key ssh.PublicKey) bool {
// check the CA of the cert
if !c.IsUserAuthority(cert.SignatureKey) {
- log.Debug("Principal Rejected: Untrusted Authority Signature Fingerprint %s for Principal: %s", gossh.FingerprintSHA256(cert.SignatureKey), principal)
+ if log.IsDebug() {
+ log.Debug("Principal Rejected: %s Untrusted Authority Signature Fingerprint %s for Principal: %s", ctx.RemoteAddr(), gossh.FingerprintSHA256(cert.SignatureKey), principal)
+ }
continue principalLoop
}
// validate the cert for this principal
if err := c.CheckCert(principal, cert); err != nil {
- // User is presenting an invalid cerficate - STOP any further processing
- log.Error("Permission Denied: Invalid Certificate KeyID %s with Signature Fingerprint %s presented for Principal: %s", cert.KeyId, gossh.FingerprintSHA256(cert.SignatureKey), principal)
+ // User is presenting an invalid certificate - STOP any further processing
+ if log.IsError() {
+ log.Error("Invalid Certificate KeyID %s with Signature Fingerprint %s presented for Principal: %s from %s", cert.KeyId, gossh.FingerprintSHA256(cert.SignatureKey), principal, ctx.RemoteAddr())
+ }
+ log.Warn("Failed authentication attempt from %s", ctx.RemoteAddr())
+
return false
}
+ if log.IsDebug() { // <- FingerprintSHA256 is kinda expensive so only calculate it if necessary
+ log.Debug("Successfully authenticated: %s Certificate Fingerprint: %s Principal: %s", ctx.RemoteAddr(), gossh.FingerprintSHA256(key), principal)
+ }
ctx.SetValue(giteaKeyID, pkey.ID)
return true
}
+
+ if log.IsWarn() {
+ log.Warn("From %s Fingerprint: %s is a certificate, but no valid principals found", ctx.RemoteAddr(), gossh.FingerprintSHA256(key))
+ log.Warn("Failed authentication attempt from %s", ctx.RemoteAddr())
+ }
+ return false
+ }
+
+ if log.IsDebug() { // <- FingerprintSHA256 is kinda expensive so only calculate it if necessary
+ log.Debug("Handle Public Key: %s Fingerprint: %s is not a certificate", ctx.RemoteAddr(), gossh.FingerprintSHA256(key))
}
pkey, err := models.SearchPublicKeyByContent(strings.TrimSpace(string(gossh.MarshalAuthorizedKey(key))))
if err != nil {
if models.IsErrKeyNotExist(err) {
- log.Warn("Permission Denied: Unknown public key : %s", gossh.FingerprintSHA256(key))
+ if log.IsWarn() {
+ log.Warn("Unknown public key: %s from %s", gossh.FingerprintSHA256(key), ctx.RemoteAddr())
+ log.Warn("Failed authentication attempt from %s", ctx.RemoteAddr())
+ }
return false
}
- log.Error("SearchPublicKeyByContent: %v Failed authentication attempt from %s", err, ctx.RemoteAddr())
+ log.Error("SearchPublicKeyByContent: %v", err)
return false
}
+ if log.IsDebug() { // <- FingerprintSHA256 is kinda expensive so only calculate it if necessary
+ log.Debug("Successfully authenticated: %s Public Key Fingerprint: %s", ctx.RemoteAddr(), gossh.FingerprintSHA256(key))
+ }
ctx.SetValue(giteaKeyID, pkey.ID)
return true